Incidence of Foot and Ankle Injuries in West Point Cadets with Pes Planus Compared to the General Cadet Population

Abstract

Background: The relationship between pes planus and injuries of the lower extremity is controversial. However, few studies have used standardized means of evaluating and defining pes planus, and none have had a controlled patient population. The objective of this study was to evaluate an ideal population of physically active individuals to establish a potential correlation between pes planus, as defined by a standardized method, and injuries to the lower extremity. Methods: A standardized technique for evaluating arch height, based on a midfoot ratio established by Harris mat print calculations, was used to assess a consecutive series of 512 newly entered West Point cadets. Pes planus was defined as more than 2 standard deviations above the mean midfoot ratio of the population. After 46 months, a retrospective chart review was done to identify lower extremity injuries sustained in this group of young healthy patients. The results of the footprint analysis were correlated with the medical record findings. Results: Thirty-three cadets were found to have pes planus; 13 had only left foot involvement, 15 had right foot only involvement, and five had bilateral pes planus. There were no cavus feet. Statistically significant relationships were seen between the degree of pes planus and total number of injuries sustained ( p = 0.007), the overall size of the foot and total number of injuries ( p = 0.041), left flat feet and left midfoot injuries ( p = 0.028), left pes planus and right midfoot injuries ( p = 0.008), left pes planus and left knee injuries ( p = 0.038), and right pes planus and right knee injuries ( p = 0.027). Women had smaller feet ( p = 0.000), smaller midfoot ratios (right, p = 0.013; left p = 0.003), yet they had an increased number of injuries (Pearson's coefficient −0.119; p = 0.007). Conclusions: The current study found significant relationships between pes planus and number of injuries sustained over a 4-year period at West Point. While women were found to have smaller feet and lesser degrees of pes planus, they sustained more injuries than men.